Safety device for punch presses



Dec. 2%, 1942.. w, J, lpsizm SAFETY DEVICE FOR PUNCH PRESSES Filed Sept. 11, 1941 2 Sheets-Sheet 1 Dec. 29;1'942. w. J. IPSEN SAFETY DEVICE FOR PUNCH PRESSES 2 Sheeis-S'neet 2 Filed Sept. 11, 1941 Patented Dec. 29, 1942 '2 35 94Q STAT This invention relates to safety devices for punch press having a safety device constructed punch presses. according to this invention mounted thereon,

At the presenttime certain punch presses are pro- Figure 2 is a fragmentary front elevation partly vided with a spring-pressed dog which is designed broken away and in section of the safety device, to stop the press when the movable die or punch is Figure 3 is a sectional view taken on the line in an uppermost position. However, this springv3-3 of Figure 2, and pressed dog is not entirely satisfactory as fre- Figure 4 is a view similar to Figure 3 with the quently the press hesitates in its operation after safety device and the stop dog in released posibeing released for starting. a cycle, and permits a tion. person to insert a hand or finger beneath the die Referring to the drawings the numeral Iii desigor punch. After hesitating momentarily, the nates generally the frame of a punch press which press completes its normal cycle of operation with is provided with a vertically movable die or punch resultant injury to the operator or any work member ll operatively connected with a rotary which may not be properly positioned relative to drive shaft l2 which is journ led in the upp the dies. It is, therefore, an object of this invenportion of the frame It. A lower stationary die tion to provide a safety attachment for a press member I3 is disposed in a position for correlawhich is correlated with the usual spring-pressed tiOII W t t moVable die I! performing the stop .dog and which is movable with the latter to desired punching or die operation. a latching or released position, but is spaced from The shaft M has mounted thereon a Wheel M the latter dog sufficiently so that'if the latterdog Which is formed with a hub or boss l5. The should be shifted to a released position and the Wheel 14 s P v d t a point o wardly fro press should hesitate in its operation, the second the shaft i2 with an open Which in the or auxiliary stop dog will automatically stop the present instance is square or rectan in nspress before any damage or injury result verse section and constitutes a keyway for re- A further object of this invention is to. provide 0 CeiVing a key abutment e b is s in combination t a punch press a pair of formed with a recess l8 communicating with the cumferentially spaced apart stop dogs correlated recess H 50 a the inner f of the key with the flywheel and drive shaft for thepress so flbutment H W111 be exposed mwardlif from the as to permit the operator to stop the press before it mner face of the Wheel A plvoted Stop completes its normal cycle of operation and after g 29 is pivotally mounted on a Pin bolt which engages an outstanding boss 22 which is the press begins its normal cycle.

A further objectof this invention is to provide a fixed to fl The dog 25 15 forms? wlth a key receiving recess or cutout 23 and 1s also safety attachment which in the normal operation of the press will be inactive, being held in an int F formed Wlth artmner a or flange 24 Whlch 13 active position'with the normal stop dog, a suffiengageable agamst of the key or cient length of time to permit the press to operate abutment n Shown m Figure its normal cycle, but in the event the press con- The 15 rocked downwardly on t plvot sumes more than the normal time in starting its 33 g? i g fi f i gii ggg g ai g cycle of operation, the attachment will become straight portion 26 and an upper offset portion 27. active to stop further operation of the press th i The upper end of the upper portion 21 is secured press being subsequently releasable for complein the lower end of a link 23 by means of pair tion of its incomplete cycle by depression of the of lock nuts 29 and 39. The link 28 is formed pedal connected with the normal stop with a pair of spaced ears 3| which are pivotally with the foregoing objects and Others which secured to the dog 29 adjacent the free end theremay hereinafter appear, the invention consists of of by means of a pivot bolt 32 engaging through the novel construction, combination and arrange the ears and the lower portion of the dog g men of parts as W e more Specifically referred The dog operating member 25 is slidable through to n il r i the mp nyin drawings, a U-shaped guide member as which has the bight wherein is Shown an embediment 0f the inven- 34 thereof secured as by fastening devices 35 to tion, but it is to be understood that changes, varithe frame It. The dog Zil is constantly urged ations and modifications may be resorted to which upwardly to a position in the path of th rotation fall within the scope of the invention as claimed. of the key or abutment H by means of a pair of In the drawings: springs 33 and 37. An upper collar 38 is secured Fi ure 1 s a fragmentary d elevation of a by means of a set screw 39 to the rod 25 and bears against the upper end of the spring 36. The lower end of the spring 36 bears against the uppermost leg 40 of the U-shaped guide member 33. The lower spring 31 at its upper end bears against a collar 4| which is fixed by means of a set screw 42 on the rod 25 between the upper leg 40 and the lower leg 43 of the U-shaped member 33. The lower end of the spring 37 bears against the upper side of the lower leg 43.

The link 28 is formed with an opening 44 therethrough at a point below the ears 3| and the forward end of a steadying link or arm 45 is pivotally mounted in the opening 44, being mounted on a pivot bolt 45. The opposite end of the link or steadying member 45 is pivotally mounted on a pivot member 41 carried by an outstanding boss 48 which is fixed relative to the frame ID.

The operating means for the rod 25 is conventional and includes means whereby the rod 25 may be pulled downwardly so as to hold the dog 26 in a released position for a sufficient length of time in order to permit the abutment or key I! to rotate relative to the dog 25. The wheel I4 and the shaft I2 are adapted to rotate in the direction of the arrow 49 as viewed in Figure 1, rotating in a counterclockwise direction. It has been found in the operation of the press with the use of the stop dog 25 that when the dog 25 is shifted to a released position the shaft l2 does not immediately rotate at the desired speed and this hesitation in the rotation of the shaft l2 frequently has the effect of damaging the work or permitting the operator of the press to insert a finger or hand between the movable die I I and the stationary die I3 thus causing injury to the operator.

In order to prevent the shaft I2 from completing a revolution thereof in the event the shaft hesitates in its movement, I have provided a second or safety dog 50 which is disposed in a position substantially ninety degrees from the dog 20. The dog 50 is pivotally mounted on a pivot member carried by an outstanding boss 52 which is fixed relative to the frame II]. The dog 55 is similar in every detail to the dog 20, being provided with a recess or bill 53 within which the abutment or key I! is adapted to engage and also is provided with a flange 54 engageable against the inner end of the abutment or key II.

In order to provide a means whereby the safety dog 55 may be automatically shifted to a released position simultaneous with the shifting of the dog 20 to a released position, I have provided a link 55 which is pivotally mounted on a pivot member 55 carried by an outstanding boss 51. The boss 51 is fixed relative to the frame III. The lower stop'dog 2D has secured thereto or formed integral therewith an upwardly and obtusely extending arm 58. The lower end portion of the link 55 is pivotally secured to the arm 58 by means of a pivot member 59. The upper portion of the link 55 is formed with an elongated slot 50 within which a pin GI carried by the dog 50 slidably engages.

In the use and operation of this safety device in the normal operation of the press through one complete cycle, the shaft I2 will make one complete revolution and the movable die I I will move downwardly and then upwardly. When the shaft I2 operates in the normal manner and the stop dog 20 is moved to a released position by downward pull on the dog operating member 25, the speed of rotation of the shaft I2 is sufficient to permit the abutment I'Iv to pass the safety dog complete its punching cycle.

59 before the two dogs 20 and are returned to a locking position. After the abutment I'I passes the safety dog 50, the two dogs 20 and 50 will move to the positions shown in Figures 1 and 3. In Figure 4, the two dogs 20 and 50 are shown in the released position which is the beginning of the punching cycle.

However, in the event the shaft I2 does not start its rotation for performing the normal punching cycle, or in other words, hesitates in its initial rotation, the time period consumed during which the abutment I1 is released from the dog 20 until the abutment I'I reaches the safety dog is sufficient to permit the dog operating member 25 to move the two dogs 20 and 50 to the locking position shown in Figures 1 and 3. In this one-quarter turn of the shaft I2 and the abutment I1, the die member I I has only completed a portion of its downward movement so that in the event any work is misplaced between the two dies II and I3 or in the event the operator of the machine inadvertently inserts a hand or the like between the two dies, the safety dog 59 will stop the shaft I2 and the downward movement of the die II before any damage is done either to the Work or the hand or arm of the operator. In the event the safety dog 50 is engaged by the abutment or key I! as shown by the dotted line position I'Ia, the key or dog 50 maybe shifted to a released position coactive with the movement of the dog 20 by downward pull on the dog operating member 25. In other words,-in the event the safety dog 50 is effective due to the hesitancy in the rotation of the shaft I 2, it is necessary for the operator of the machine to exert a second pulling operation on the dog operator 25 in order to permit the shaft l2 to The safety dog 50 is so positioned on the press ID as to be effective only on the downward movement of the movable die II as it is on this portion of the punching cycle that any damage may be done to either the work or the operator if the operator should inadvertently insert a hand or finger beneath the movable die. The mounting of the safety dog 50 on the press will not affect the normal operation of the press, but only affects the operation of the press when the opera-tion is subnormal.

What I claim is:

1. In combination a punch press including a rotatable element and a manually releasable pivoted stop member normally biased to a position in the path of said element for stopping rotation of said element, a second pivoted stop member spaced from said first stop member for stopping said element after the latter is released from said first stop member, said stop members having spaced apart pivot axes, and means connecting said stop member with said first stop member for simultaneous operation with the latter.

2. In a punch press provided with a manually releasable spring-pressed stop member; a safety attachment comprising an auxiliary stop member disposed in a position spaced from said first stop member, and a linkage connecting said stop members together for simultaneous movement to either released or operative position, said first stop member normally effecting a stoppage of the press at the completion of each cycle of operation, and said second stop member effecting a stoppage of the press after beginning of a cycle of operation in the event the starting period of a cycle consumes more than the normal period of time.

3. In a punch press, a rotatable abutment carried by said press, a stop dog, means pivotally mounting said dog on the press in a position for engagement with said abutment, an operating member connected with said dog, means engageable with said operating member constantly urging said dog to a position for engagernent with said abutment, a second stop dog, means pivotally mounting said second dog in a position for engagement with said abutment at a point spaced from said first dog, and means connecting said dogs together for simultaneous operation, said second dog being so spaced from said first dog as to permit passage of said abutment upon normal rotation of the latter but to arrest rotation of said abutment upon delayed starting thereof.

4. In a punch press having a releasable springpressed stop dog for stopping rotation of the drive shaft at the end of each punching cycle and subsequently releasing the drive shaft for one complete revolution of the latter to perform a punching cycle, said shaft having an abutment fixed thereto for engagement with said stop dog;

a safety attachment for stopping rotation of said shaft in the event the shaft fails to immediately start rotation upon movement of said stop dog to a released position, said attachment cornprising a safety dog member, means pivotally mounting said member on the press at a point circumferentially spaced from said stop dog in a position for engagement with said abutment, a connecting link pivotally connected to both of said dogs for effecting operation of said safety dog simultaneously with said stop dog, and means cngageable With said link intermediate the ends thereof pivotally mounting said link on the press.

5. A safety attachment for a punch press provided with a spring-pressed pivoted stop dog engageable with a rotary abutment; said attachment comprising a safety dog, means pivotally supporting said safety dog in circumferentially spaced relation with respect to said stop dog, and means connecting said safety dog with said stop dog for operation of said safety dog constantly with and by said stop dog.

WILLIAM J. IPSEN. 

